1. Field of the Invention
The present invention relates to a resin-sealed power semiconductor module, formed by transfer molding, which is excellent in terms of productivity. The present invention particularly relates to a resin-sealed power semiconductor module, formed by transfer molding, which is small in size, realizes large-current operation, and is highly reliable.
2. Description of the Background Art
One of the resin-sealed power semiconductor modules formed by transfer molding, which is small in size, capable of efficiently discharging to the outside the heat generated due to its operation, and capable of large-current operation, is the one in which: power semiconductor elements such as an IGBT and the like are mounted on a circuit pattern joined to a metal heat sink base; and main terminals and control terminals for external connection are joined to the circuit pattern so as to be substantially perpendicular to a surface of the circuit pattern.
A copper block, a cylinder having a screw hole, and a nut fixed by resin molding, are each used for a main terminal connected to a main circuit of this power semiconductor module. The main terminal that is a copper block is joined to external wiring by soldering. The main terminal that is a cylinder having a screw hole, or the main terminal in which a nut is fixed by resin molding, is connected to external wiring by a bolt. Further, as a terminal that connects the power semiconductor module to an external control circuit, a female connector is used in such a manner that a pin-type terminal provided on the control circuit is connected to the female connector (see, e.g., Page 7 to 9, FIGS. 2 and 6 of Japanese Laid-Open Patent Publication No. 2007-184315 (hereinafter, referred to as Patent Document 1)) .
To the power semiconductor module sealed with resin by transfer molding, which is described in Patent Document 1, external wiring through which a large current is applied to the main terminal is fixed by thread connection or soldering. For this reason, the external wiring cannot be readily removed. Thus, there is a problem regarding repairability in a case where defects occur.
Patent Document 1 describes a connector configuration, of a control terminal of the power semiconductor module, to which a pin can be detachably connected. Accordingly, the problem of the power semiconductor module regarding repairability can be overcome by providing the main terminals of the power semiconductor module in the form of cylindrical external terminal communication sections each having such a structure as to allow an external terminal to be connected thereto by press-in connection, typically press fitting.
However, the power semiconductor module, in which the cylindrical external terminal communication sections are used as terminals to which external terminals are connected by press-in connection, has the following problem: even if the external terminals are already inserted into the cylindrical external terminal communication sections, when the power semiconductor module is used under the condition of high humidity, moisture enters the inside of the cylindrical external terminal communication sections; accordingly, corrosion occurs at the inside of the cylindrical external terminal communication sections and at a wiring pattern, causing deterioration in connections between the cylindrical external terminal communication sections and the external terminals; as a result, contact resistance and thermal resistance increase.
Also, even in a power semiconductor module which uses, as terminals, cylindrical external terminal communication sections to which external terminals are connected by soldering, there is a case where moisture enters a boundary between a cylindrical external terminal communication section and transfer molding resin. Accordingly, there is a problem that the outer wall of the cylindrical external terminal communication section and the wiring pattern are corroded.